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November 24, 2006

Cleaner Iron Production with Corex Process

A special manufacturing process is making the production of iron much more environmentally friendly. The outstanding feature of the “Corex process” is that it uses conventional coal instead of coking coal, the customary ingredient.

Siemens is currently building the world’s largest Corex-based plant in China. Scheduled to begin operation in late 2007, this steel mill requires no coking plant, an element that typically accounts for a major share of emissions.

Corex is a smelting reduction process: Coal gasification, iron ore reduction, and liquefaction of the resulting iron are combined in one process. The gases produced can immediately be used for heating or for generating electricity in a gas and steam turbine power plant.

This plant burns uncoked coal, which means that the coking plant – one of the primary sources of emissions from an iron and steel plant – is now redundant. At the high gasification temperatures of the coal in the smelting reactor, organic compounds are completely reduced to their basic gaseous components and organic sulfur hydrides are converted to carbonated and/or hydrogenous gases. In a separate process in a melter gasifier, these vile smelling, and highly toxic, compounds are almost completely combined in sponge iron, aggregates, and slag.

In conventional pig iron production at iron works, coking coal is first mixed with charge consisting of pellets, sinter and lump ore, and then the mixture is put into a blast furnace. At the base of this giant, bell-shaped furnace injected hot air burns the coking coal up into carbon monoxide at 2,000 degrees Celsius. In the upper part of the furnace the soaring carbon monoxide withdraws the oxygen from the iron oxide in the iron ore. Because of the high temperature the reduced ore melts to liquid pig iron.

As a result of this traditional process with coking plant, powder metal facility and blast furnace, 1.4 kilograms of sulfur dioxide are created for each ton of pig iron. According to measurements taken by the TÜV Rheinland, with the Corex process this figure is reduced to only 40 grams, a reduction of 97%, and discharge of dust and nitrogen oxides is cut by more than 90 percent.

One of the disadvantages of the process is caused by the strict particle size requirements for process, the process cannot tolerate coal particle sizes below 16 mm. A decrease in the mean particle size (MPS) reduces the permeability of the char bed, which results in gas channeling and a drop in the hot metal temperature and quality. The optimum MPS of coal used in the COREX process should be maintained between 20 and 30 mm.

Between the mine and the end user, lump coal is subjected to a number of mechanical actions with a resulting increase in the quantity of fines coal. Typically, the coal used in the process is sized at the mill at +16.0 mm with a top size as high as 70 to 80 mm. Fines, coal less than 16.0 mm, represents a reduction in the quantity of coal of the correct size for use in the COREX process and thus a higher net cost for the coal.

Compared to a blast furnace, COREX is a more complex process using 100 % oxygen and coal instead of coke.

China ’s booming economy and increasing urbanization are also leading to an upsurge of heavy industry. China’s metropolitan areas are now among the most polluted regions on earth, so new steel works are generally built with very environmentally friendly technology, and far from cities. Scheduled to become operational in the autumn of 2007, the new plant of the Baosteel subsidiary Baoshan in Luojing is using the Corex process.

When Baosteel decided to go with the environmentally-friendly Corex process, as opposed to the conventional blast furnace, they did so after exhaustive economic analysis and with stringent environmental legislation in mind. This is the first installation of the C-3000 COREX® module worldwide and has a pig iron capacity of 1.5 million tons per year; it is equivalent to a mid-sized blast furnace. The Corex export gas is fed into a modern gas and steam power plant for electricity generation; and into the iron and steel works to be used for heating. Baosteel is currently planning another Corex plant, again with a capacity of 1.5 million tons of pig iron.

Three plants, Pohang Iron and Steel Company in South Korea, Saldana in South Africa, and Jindal Vijayanagar Steel Limited in India are already successfully operating the process.

Comments

This is an impressive development, and I say that as a person who once spent time breathing in the vicinity of a coking plant. They are vile. While I wouldn't call 16 mm a "particle", I don't see what the big deal is about the fines. They can be burned for energy, can't they?

We have supplied the refractories to plant with Corex process such as Baosteel of 1.5MTPA and Posco/Korea through Chosun Refractory Company. Does someone want to import the materials that used in Corex Unit?

i am reading the corex proces of steel makiing.learned about thge usage of corex gas in steam generators.
please inform me the ignition temperasture of corex gas used in boilers of thermal plants.
thanking you
d.v.s.narayana

Which is the proces wherein any size of iron ore and coal can be the inout material?
Use of hydrogen as reductant would solve most of the polution problems. Is there such a process for iron manufacturing?

I am ahmed shah in Corex Department of Essar steel hazira limited.
I want to know that C-3000, has adopted the gimble technology for charging. so, is there any effect on any process . does it smoothening the process , is there advantage by applying this gimble design.

About corex and latest developments
COREX( Coal reduction process) is an smelting reduction process.For liquid iron production
In which There are two parts.
1. Reduction shaft
2. Melter gasifier

1. Reduction shaft: As the name indicates the materials which are charged like Iron ore pellets or lumps and some amount of coke and other additives are reduced in this shaft which takes about five to six hrs depend upon operating conditions.the final products of reduction shaft is hot DRI and other additives which is directly charged into melter gasifier through screw conveyor from a closed chamber which prevents it from further oxidation.

2. Melter gasifier : In melter gasifier along with hot DRI coal and some amount of coke and quartzite is added. here from the name here melting of hot dri, formation of slag as well as gas formation takes place ( which is rich in CO) .her the total time taken is near about three hrs.

The main advantage of corex process is that it uses non coking coal as a fuel, provides very rich gas after process( calorific value : 1600-1850 kcal) and the environment friendly becuse in blast furnace process we require coke while making coke enormous amount of toxic gases are generted here we eliminate coking process.

But now a days a new technology came known as finex technology came which directly uses iron ore fines and coal fines for producing hot metal.Presently only it is running in posco- pohang works which is in korea( a 1.5 million ton). and posco is planning to implent this technology in India project ( orissa-paradip) which overcomes the swapping of iron ores. Definately this process is helpful in future iron production in economical and large scale.for more information mail me on

from the information i search, there is no way to has 100% coal. the information i get didn't give any explaination on it. it only mention a few coke is added to the coal for melther gasfier. so, can you explain why is needed some coke into coal??
and, by adding this coke, the corex process still environmental friendly???why??
hydrogen is a great reduction agent, at here, why it cannot be used for as a main heat supply?? before that,i want to sure that, is it oxidize the hydrogen gas is exorthermic reaction that similar to combustion of carbon and oxygen??
thank...

Regarding ans of question of leave that why is needed some coke into coal??
and, by adding this coke, the corex process still environmental friendly???why??
hydrogen is a great reduction agent, at here, why it cannot be used for as a main heat supply??

Ans .. The answer is that here we are adding coke because in melter gasifier as well as in reduction shaft we require permeability .
And about hydrogen yes hydrogen is thrice times more effective gas as compared to CO in low temperature in the same side the reaction of hydrogen makes the reaction endothermic.

Ans . That in corex process we are producing DRI in reduction shaft at 850 degree centigrade and after we are smelting that DRI in melter gasifier to Get liquid hot metal just like in Blast furnace. So, there is no question regardingadvantages of corex over dri process.

As question by mohamed abd elgalil
Que. does any one know about refractory material used in corex melter gasifier ????????
Ans . The ans is that it has in reduction shaft simply alumina based bricks whereas in melter gasifier at dome portion there is alumina gunniting at side alumina and silica based bricks
and in hearth same as like blast furnace graphite and carbon blocks

For more information you have to contact seimens-VAi who is the technological supplier of that

"Similar design of all metal, glass and other energy intensive production...."

Just one question: How do you have energy intensive industrial production with low energy intensive wind? It would require so many windplants covering the whole world as to be prohibitively expensive to build them all. Not to even mention the eyesore. Energy intensive nuclear power or geothermal hydrogen for steel production would be far more practical.